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1. Intermitent or not, you need to be sure of the result. Also, Apple will still work on it even if its intermitent.

2. You won't be able to show your results obviously. However, you will be able to clearly explain the steps you took to diagnose your device. Basically, you'll let them know you have tried to work it out before coming to them. Furthermore, it shows that your gave them steps to take should they need to replicate the issue. Genius' (almost 95% of them) will take this and roll with it for a replacement. You showed a strong case for it

That does make sense. I realize they need data in order to address the problem. I have turned on the analytic's reporting in case that can provide information for them. I have also purchased a GPS Diagnostic App that will give me visibility of the raw GPS data the phone is getting. That could prove invaluable in troubleshooting this.

I am really curious if the iPhone has the capability to switch over to the Watch GPS in the event of a failure though. It would really explain the situation and does seem to fit with what I saw yesterday. I normally only ever see my Watch charge level fall off like that when I use the GPS for an extended workout. If the iPhone was leaning on the Watch GPS for some strange reason it would explain not only the charge level issue but also the choppy updating as the data is sent from the Watch to the iPhone (a slow connection).
 
As Info. . .
Many people have the GPS issue. It has been complained about on other forums too.
The GPS will work "IF" you are standing still but if you are moving the GPS functionality stops.

I am on my second new iPhone-X since mid December and BOTH phones have had the exact same problem: No GPS function while moving.
If you come to a complete STOP then (after a brief wait) the iPhone-X can find itself and all map programs work fine.
Once you go back onto the highway and start moving again... No GPS functionality and your maps and Nav apps become useless.

My backup phone is my old 6s+ and it is setup exactly the same as my new iPhone-X and the old 6s+ NEVER has a GPS problem.
<go figure>
 
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